Breathing devices like Closed and Semi Closed Circuit Rebreathers and other closed loop breathing systems rely on electronic control systems to monitor the oxygen level through the use of oxygen sensors and to process the system information to determine if a solenoid or valve needs to be opened in order to add more oxygen into the breathing system. Up to now, this has involved a complicated and interconnected array of components to accomplish this task. The batteries, control electronics, sensors, and gas control devices all must be connected with cables and varying levels of connectors. Breathing systems to date have neither considered these subcomponents as a complete system nor have the control systems in general been considered as an integral part of the system design for the rebreather itself. The resultant breathing system designs have therefore treated the control system as both a separate system from the rebreather and have considered the individual components of the electronic control and sensing system as generally separate design elements. All of the control system subcomponents and parts have maintenance and reliability issues that either requires regular maintenance or possible replacement. All of the necessary electronic and mechanical interconnects between these components represent points of failure as well as increases assembly time, maintenance, and system cost.
All breathing device control systems require maintenance and have attendant diagnosis and or possible replacement issues. Successful diagnosis and replacement can be as easy as replacing a battery or sensor to as complicated as sending the entire breathing unit in for a factory trained technician to diagnose and service. The latter option comes at an additional cost of significant down time. On current, non-modular systems, parts can be very difficult to remove and replace; especially in the field or on short notice. A significant array of available spare parts is therefore necessary to be able to repair any control related failure in most breathing systems.
Manufacturer upgrades to the control system typically consists of sending the entire unit or a significant portion thereof back for retrofitting. This is both costly and inefficient.
In rebreathing systems, a popular implementation has been that the separate pieces have been combined into a single large “head” which comprises the entire top assembly of a rebreather. This “head” typically including breathing hose mounts, scrubber and breathing bag supply paths, some of the electronics, sensors and or the gas injection solenoid. The “head” therefore, is a substantially sized and priced piece of the breathing system with a great deal more functionality and cost than just the control subsystem and includes a great deal of mechanically oriented parts and mountings which are not as likely to fail or need replacement as the control and sensing subsystem. Within the “head”, the components of the control and sensing subsystem are still treated as individual components with all the attendant difficulties remaining concerning cost and reliability.